Vacuum pump

ABSTRACT

Each of the stationary blade portions is formed by two or more divided stationary blade portions, and has abutting ends in both circumferential ends, the stationary blade portion is formed by abutting the abutting ends of the divided stationary blade portions with each other. Each of the divided stationary blade portions has an outer circumferential rim nipped by the spacers, an inner circumferential rim positioned in a front end on the inner circumferential side of the stationary blade portion, and a plurality of stator blades formed between the outer circumferential rim and the inner circumferential rim. In abutting ends of the outer circumferential rims where the plurality of divided stationary blade portions is abutted with each other, at least one of the outer circumferential rims has a cutout forming a gap together with the other facing outer circumferential rim.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a vacuum pump having an exhaust portion formed by rotating blade portions and stationary blade portions.

2. Description of the Related Art

In a vacuum pump such as a turbo-molecular pump, a rotor having rotating blade portions arranged in multiple stages is rotated at high speed in a pump container, and a gas molecule is moved from the intake port side to the exhaust port side by the rotating blade portions and stationary blade portions arranged between the stages of the rotating blade portions.

Each stage of the rotating blade portions has rotor blades, and each stage of the stationary blade portions has stator blades. The stationary blade portions are supported at predetermined intervals by spacers arranged on outer circumferences of the stationary blade portions. The stationary blade portions are formed into one ring shape by combining a pair of halved ring shape members. That is, one ring is formed by abutting two abutting ends each other serving as abutting portions of the halved ring shape members. The rotor blades and the stator blades are formed so as to be inclined with respect to a rotation surface of the rotor.

As a method of manufacturing the stationary blade portions, there are a method of forming by mechanical working and a method of forming by plastic working. The method of manufacturing by the plastic working is advantageous in terms of cost.

In the method of forming by the plastic working, a plurality of stator blades formed by pressing a plate and arranged at a predetermined inclination angle along the circumferential direction is coupled by an inner circumferential rim and an outer circumferential rim, so that a stationary blade portion is manufactured. Due to variation at the time of the working, there is sometimes a case where a circumferential length of the halved ring shape members is longer than designed size. Therefore, when one ring is formed by abutting the abutting ends of the halved ring shape members with each other, the abutting ends of the halved ring shape members are overlapped with each other or the abutting ends are warped by reactive force of the abutting ends against each other.

Conventionally, there is a known structure that slits are provided on an abutting surface of an inner circumferential rim in a state where the halved ring shape members are abutted with each other (for example, refer to JP 2006-77713 A).

As described above, when the circumferential length of the halved ring shape members is varied at the time of the working, overlap and warpage are generated in the stationary blade portion. Japanese Unexamined Patent Application Publication No. 2006-77713 describes neither such a problem nor a measure against this.

SUMMARY OF THE INVENTION

A vacuum pump has an exhaust function portion in which stationary blade portions nipped by spacers are respectively arranged between rotating blade portions arranged in multiple stages. Each of the stationary blade portions is formed by two or more divided stationary blade portions, each of the divided stationary blade portions has abutting ends in both circumferential ends, the stationary blade portion is formed by abutting the abutting ends of the divided stationary blade portions with each other, each of the divided stationary blade portions has an outer circumferential rim nipped by the spacers, an inner circumferential rim positioned in a front end on the inner circumferential side of the stationary blade portion, and a plurality of stator blades formed between the outer circumferential rim and the inner circumferential rim, and in abutting ends of the outer circumferential rims where the plurality of divided stationary blade portions is abutted with each other, at least one of the outer circumferential rims has a cutout forming a gap together with the other facing outer circumferential rim.

According to this invention, even in a case where a circumferential length between abutting ends is formed to be longer than designed size due to size variation at the time of working of divided stationary blade portions, at the time of assembling a stationary blade portion, ends of outer circumferential rims of a plurality of divided stationary blade portions can be suppressed from being overlapped with each other, or generation of warpage can be suppressed in the divided stationary blade portions themselves, namely the stationary blade portion itself.

Preferably, each of the divided stationary blade portions is manufactured from a flat plate into the same shape, an abutting end surface of the inner circumferential rim and an abutting end surface of the outer circumferential rim are formed as a first abutting surface in the one abutting end of the divided stationary blade portion, an end surface of the inner circumferential rim, an end surface of the outer circumferential rim, and an end surface of an edge member forming an opening portion are formed as a second abutting surface in the other abutting end, and the first abutting surface and the second abutting surface are abutted with each other so as to form the stationary blade portion.

Preferably, the cutout is provided in the outer circumferential rim as a rectangular shape with a predetermined width in the circumferential direction and a predetermined length in a radial direction.

Preferably, a bending portion bent from the inner circumferential rim is provided in at least one of end surfaces of the inner circumferential rims where the plurality of divided stationary blade portions is abutted with each other.

Preferably, the gap is determined based on maximum tolerance α of circumferential length between both the abutting ends, and/or maximum tolerance β between an outer circumferential surface of the stationary blade portion assembled from the divided stationary blade portions and an inner circumferential surface of the spacer.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a turbo-molecular pump serving as one embodiment of a vacuum pump according to this invention;

FIG. 2 is an enlarged view of a region II in FIG. 1;

FIG. 3 is a plan view of a stationary blade portion;

FIG. 4 is an enlarged perspective view of a region IV in FIG. 3;

FIG. 5 is a plan view of a half-disc plate for illustrating a manufacturing method of the stationary blade portion;

FIG. 6 is a plan view of the half-disc plate for illustrating a step following FIG. 5;

FIG. 7 is an enlarged view of a region VII in FIG. 6;

FIG. 8A is a plan view of a punch, and FIG. 8B is a perspective view of the punch;

FIG. 9A is a plan view of a die, and FIG. 9B is a perspective view of the die;

FIG. 10 is views for illustrating a method of manufacturing a stator blade by drawing with using a punch PU and a die DI, FIG. 10A is a sectional view taken along line Xa-Xa in FIG. 6 at the time of the drawing, and FIG. 10B is a sectional view taken along line Xb-Xb in FIG. 6 at the time of the drawing;

FIG. 11 is an enlarged perspective view of Embodiment 2 in major parts of the stationary blade portion of the present invention; and

FIG. 12 is an enlarged perspective view of Embodiment 3 in the major parts of the stationary blade portion of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Embodiment 1

Hereinafter, referring to the drawings, a vacuum pump according to the present invention will be described with a turbo-molecular pump as one embodiment.

(Entire Configuration of Vacuum Pump)

FIG. 1 is a sectional view of a turbo-molecular pump 1, and FIG. 2 is an enlarged view of a region II in FIG. 1.

The turbo-molecular pump 1 includes a pump container 11 formed by a casing member 12 and a base 13 fixed to the casing member 12.

The casing member 12 has a substantially cylindrical shape, and formed by for example SUS, and an upper flange 21 is formed in an upper end. A disc shape intake port 15 is formed on the inner side of the upper flange 21 of the casing member 12. Through holes 22 for bolt insertion are formed in the upper flange 21 at substantially equal intervals along the circumferential direction. The turbo-molecular pump 1 is attached to an external device such as semiconductor manufacturing device by inserting bolts 92 into the through holes 22 of the upper flange 21.

A rotor 4 and a rotor shaft 5 attached coaxially with an axis of the rotor 4 are accommodated in the pump container 11. The rotor 4 and the rotor shaft 5 are fixed by bolts 91.

The rotor 4 includes a rotor upper portion 4A, and a rotor lower portion cylindrical portion 4B jointed to a lower surface of the rotor upper portion 4A. The rotor upper portion 4A is made of for example an aluminum alloy. In the rotor upper portion 4A, a plurality of rotating blade portions 6 formed in a radial manner and arranged in the circumferential direction is arranged in multiple stages at intervals in the axial direction of the rotor 4. The rotating blade portions 6 are formed at a predetermined inclination angle with respect to a rotation surface of the rotating blade portions 6.

As shown in FIG. 2, stationary blade portions 70 having stator blades 71 (refer to FIG. 3) are arranged between the stages of the plurality of rotating blade portions 6.

The stationary blade portions 70 are formed into one ring shape by combining a pair of halved ring shape members. Each of the stationary blade portions 70 is nipped by ring-shaped spacers 8 arranged along an inner circumferential surface of the casing member 12, and the stationary blade portions are laminated in multiple stages (seven stages in the example shown in the figure). An upper surface of the uppermost spacer 8 is abutted with an inner surface of the upper flange 21 of the casing member 12, and a lower surface of the lowermost spacer 8 is abutted with an upper surface of an upper flange 13 a of the base 13. Therefore, the stationary blade portions 70 are given force in the rotation shaft direction and supported via the spacers 8 between the inner surface of the upper flange 21 of the casing member 12 and the upper surface of the upper flange 13 a of the base 13. In such a way, the rotating blade portions 6 and the stationary blade portions 70 are alternately laminated in multiple stages, so as to form a high-vacuum blade exhaust portion.

A ring shape threaded stator 9 is fixed to the base 13 by bolts 94 at the outer circumferential side of the rotor lower portion cylindrical portion 4B. A threaded groove portion 9 a is formed in the threaded stator 9. A low-vacuum threaded groove exhaust portion is formed by the rotor lower portion cylindrical portion 4B of the rotor 4 and the threaded stator 9.

It should be noted that although the structure of forming the threaded groove portion 9 a in the threaded stator 9 is shown as an example in FIG. 1, the threaded groove portion 9 a may be formed on an outer circumferential surface of the rotor lower portion cylindrical portion 4B.

The base 13 is made of for example an aluminum alloy, and a center tube portion 14 in which a disc shape hollow part is formed for inserting the rotor shaft 5 is formed in a center part of the base 13. On the inner side of the center tube portion 14, a motor 35, (two) radial magnetic bearings 31, (a pair of upper and lower) thrust magnetic bearings 32, radial displacement sensors 33 a, 33 b, an axial displacement sensor 33 c, mechanical bearings 34, 36, and a rotor disc 38 are attached.

The rotor shaft 5 is supported by the (two) radial magnetic bearings 31 and the (pair of upper and lower) thrust magnetic bearings 32 in non-contact manner. A position of the rotor shaft 5 at the time of rotation is controlled based on a radial position and an axial position detected by the radial displacement sensors 33 a, 33 b and the axial displacement sensor 33 c. The rotor shaft 5 rotatably and magnetically floated up by the magnetic bearings 31, 32 is driven and rotated at high speed by the motor 35. By driving and rotating the rotor shaft 5, the rotor upper portion 4A coupled to the rotor shaft 5 is rotated and all the rotating blade portions 6 are integrally rotated.

The mechanical bearings 34, 36 are mechanical bearings for emergency, and when the magnetic bearings 31, 32 are not operated, the rotor shaft 5 is supported by the mechanical bearings 34, 36.

An exhaust port 16 is provided in the base 13, and an exhaust opening 16 a is provided in the exhaust port 16.

A lower flange 23 of the casing member 12 and the upper flange 13 a of the base 13 are fixed by bolts 93 through a seal member 42, so that the pump container 11 is formed.

As described above, the vacuum pump of the embodiment is a vacuum pump having an exhaust function portion in which the stationary blade portions 70 supported by the spacers 8 are respectively arranged between the rotating blade portions 6 arranged in multiple stages.

Hereinafter, the stationary blade portions 70 will be described in detail.

(Description of Stationary Blade Portion 70)

FIG. 3 is a plan view of the stationary blade portion 70 shown in FIG. 1, and FIG. 4 is an enlarged perspective view of a region IV in FIG. 3.

The stationary blade portion 70 is formed by combining two divided stationary blade portions 70A, 70B serving as the halved ring shape members. The divided stationary blade portions 70A, 70B are formed into the same shape. Each of the divided stationary blade portions 70A, 70B has an opening 83 in a center part, and serves as a half annular body in a plan view (hereinafter, also referred to as a half-disc shape for convenience). Each of the divided stationary blade portions 70A, 70B includes an outer circumferential rim 73 a, an inner circumferential rim 72 a, and the plurality of stator blades 71 extended in a radial manner with predetermined width in the circumferential direction between the outer circumferential rim 73 a and the inner circumferential rim 72 a.

As described later, the divided stationary blade portion 70A has abutting ends FA1 and FA2, and the divided stationary blade portion 70B has abutting ends FB1 and FB2. Both the circumferential ends of the divided stationary blade portions 70A, 70B are respectively formed into different shapes. Referring to FIG. 4, in the one circumferential end FA1 of the divided stationary blade portion 70A, an exhaust opening 79 exists between the inner circumferential rim 72 a and the outer circumferential rim 73 a and the circumferential rims are separated from each other. Meanwhile, in the other circumferential end FA2 of the divided stationary blade portion 70A, the inner circumferential rim 72 a and the outer circumferential rim 73 a are connected by a bridge 70S forming the exhaust opening 79.

A cutout K is provided in one end 73 a 1 of the outer circumferential rim 73 a of the divided stationary blade portion 70A and one end 73 b 1 of an outer circumferential rim 73 b of the divided stationary blade portion 70B. The cutout K is formed so as to separate the abutting end FA1 and the abutting end FB2 or to separate the abutting end FB1 and the abutting end FA2.

The one abutting end FA1 of the divided stationary blade portion 70A and the other abutting end FB2 of the divided stationary blade portion 70B are abutted with each other, and the other abutting end FA2 of the divided stationary blade portion 70A and the one abutting end FB1 of the divided stationary blade portion 70B are abutted with each other. In other words, one end 72 a 1 of the inner circumferential rim 72 a of the divided stationary blade portion 70A and the other end 72 b 2 of an inner circumferential rim 72 b of the divided stationary blade portion 70B are abutted with each other, and the other end 72 a 2 of the inner circumferential rim 72 a of the divided stationary blade portion 70A and one end 72 b 1 of the inner circumferential rim 72 b of the divided stationary blade portion 70B are abutted with each other.

(Description of Cutout K)

In a case where the divided stationary blade portions are manufactured as designed values, a straight line connecting an abutting surface between the abutting end FA1 and the abutting end FB2 and an abutting surface between the abutting end FA2 and the abutting end FB1 passes through center O of a true circle formed by the divided stationary blade portions 70A and 70B. However, at the time of manufacturing the divided stationary blade portions 70A, 70B by plastic working, the divided stationary blade portions 70A, 70B may sometimes be formed in such a manner that a circumferential length between the abutting ends FA1 and FA2 or between the abutting ends FB1 and FB2 is longer than designed size. In this case, there is a fear that both the divided stationary blade portions 70A, 70B are overlapped with each other in the abutting ends or the stationary blade portion 70 itself is warped by reactive force of both the abutting ends against each other.

In this embodiment, the cutout K shown in FIGS. 5, 6 is provided in the one abutting end FA1 of the divided stationary blade portion 70A and the cutout K is provided in the one abutting end FB1 of the divided stationary blade portion 70B. In a state where the abutting end FA1 and the abutting end FB2 are abutted with each other and the abutting end FA2 and the abutting end FB1 are abutted with each other, a gap S corresponding to the cutout K is formed between the one end 73 a 1 of the outer circumferential rim 73 a of the divided stationary blade portion 70A and the other end 73 b 2 of the outer circumferential rim 73 b of the divided stationary blade portion 70B. Similarly, a gap S corresponding to the cutout K is formed between the one end 73 b 1 of the outer circumferential rim 73 b of the divided stationary blade portion 70B and the other end 73 a 2 of the outer circumferential rim 73 a of the divided stationary blade portion 70A.

This gap S is determined based on maximum tolerance α of the circumferential length between both the abutting ends, maximum tolerance β between an outer circumferential surface of the stationary blade portion 70 assembled from the divided stationary blade portions and an inner circumferential surface of the spacer 8, or the like.

(Detailed Description of Stator Blade 71)

Although details will be described later, the stator blades 71 of this embodiment are manufactured by drawing. As shown in FIG. 4, the stator blades 71 formed in the divided stationary blade portions 70A, 70B are extended in a radial manner with predetermined width in the circumferential direction between the outer circumferential rim 73 a and the inner circumferential rim 72 a, and inclined at a predetermined blade angle with respect to a stationary blade portion main body 70H so as to form the plurality of exhaust openings 79. That is, the stator blade 71 stands from and is connected to the stationary blade portion main body 70H in a bent portion 70R extended linearly in the radial direction on a plane of the stationary blade portion main body 70H. The stator blade 71 is separated from the stationary blade portion main body 70H on the side of a front end side portion 77 which is the opposite side of the stationary blade portion main body 70H. A height of the front end side portion 77 of the stator blade 71 from the stationary blade portion main body 70H, that is, a blade height is formed to be higher on the outer circumferential side than the inner circumferential side.

The stator blade 71 is formed into a rectangular shape elongated in the radial direction in a plan view. This rectangular shape is formed by the bent portion 70R serving as a long side, the front end side portion 77 serving as a long side, an outer circumferential side end 71So serving as a short side, and an inner circumferential side end 71Si serving as a short side.

The divided stationary blade portions 70A, 70B respectively include inner circumferential side support portions 75 for connecting the inner circumferential side ends 71Si of the stator blades 71 to the inner circumferential rim 72 a or 72 b, and outer circumferential side support portions 76 for connecting the outer circumferential side ends 71So of the stator blades 71 to the outer circumferential rim 73 a or 73 b.

The inner circumferential side support portion 75 is formed over the entire length of the inner circumferential side end 71Si of the stator blade 71. The outer circumferential side support portion 76 is formed in correspondence to a part of the outer circumferential side end 71So of the stator blade 71. That is, the outer circumferential side support portion 76 is provided from the bent portion 70R where the stator blade 71 is bent from the stationary blade portion main body 70H to an intermediate part of the front end side portion 77, and an opening portion 78 is provided on the front end side. The opening portion 78 communicates with the exhaust opening 79 provided between the front end side portion 77 and the stationary blade portion main body 70H.

As described above, since the stator blade 71 is supported by the outer circumferential side support portion 76 connected to the outer circumferential rim 73 a and the inner circumferential side support portion 75 connected to the inner circumferential rim 72 a, the stator blade has large rigidity. The blade height is greater on the outer circumferential side than the inner circumferential side. However, since the opening portion 78 is formed in the outer circumferential side end 71So on the side of the front end side portion 77, generation of cracking in the outer circumferential side support portion 76 can be suppressed at the time of the drawing.

(Manufacturing Method of Divided Stationary Blade Portion)

Next, referring to FIGS. 5 to 10, a manufacturing method of the divided stationary blade portions 70A, 70B will be described.

The divided stationary blade portions 70A and 70B are manufactured by the same manufacturing method. A manufacturing method of the divided stationary blade portion 70A as a representative will be described.

This manufacturing method includes a step of preparing a half-disc plate 70P, a step of forming radial cut lines 81 in the half-disc plate 70P and forming the cutout K in the one end 73 a 1 of the outer circumferential rim 73 a, a step of forming openings 82 in the circumferential direction in outermost circumferential parts of the radial cut lines 81 of the half-disc plate 70P, and a step of forming the stator blades 71 by the drawing.

Firstly, the half-disc plate 70P serving as a metal half-disc member in which the half-disc opening 83 is provided on the inner circumferential side is prepared. An aluminum alloy, stainless steel, and the like can be used as a material of the half-disc plate 70P.

As shown in FIG. 5, the plurality of straight cut lines 81 is formed in a radial manner in the half-disc plate 70P. The cutout K is formed in the one end 73 a 1 of the outer circumferential rim 73 a at the same time or in a different step. A radial length of the cut lines 81 is a radial length of the stator blades 71. The cut lines 81 and the cutout K can be formed by pressing or etching. Edges of the cut lines 81 serve as the front end side portions 77 after the drawing.

Next, as shown in FIG. 6, the substantially rectangular openings 82 along an outer circumferential surface 84 of the half-disc plate 70P are formed in outer circumferential ends of the cut lines 81. Although the openings 82 are formed by the pressing for efficiency, the openings may be formed by the etching. The openings 82 serve as the opening portions 78 after the drawing. It should be noted that the cutout K may be not formed in the above step of forming the cut lines 81 but can be formed at the same time as formation of the openings 82 or after the formation.

By a die and a punch, the stator blades 71 are drawn from the half-disc plate 70P. Hereinafter, referring to FIGS. 7 to 10, the drawing will be described in detail.

FIG. 7 is an enlarged view of a region VII in FIG. 6. In FIG. 7, a region 76 a shown by hatching is a region becoming the outer circumferential side support portion 76 for connecting the stationary blade portion main body 70H and the outer circumferential rim 73 a by the drawing. A length lo of the opening 82 is desirably less than a half of a length L of the entire outer circumferential side end 71So of the stator blade 71.

FIG. 8A is a plan view of the punch, FIG. 8B is a perspective view of the punch, FIG. 9A is a plan view of the die, and FIG. 9B is a perspective view of the die. FIGS. 10A and 10B are views for illustrating the method of forming the stator blade 71 by the drawing with using a punch PU and a die DI, FIG. 10A is a sectional view taken along line Xa-Xa in FIG. 6 at the time of the drawing, and FIG. 10B is a sectional view taken along line Xb-Xb in FIG. 6 at the time of the drawing.

As shown in FIGS. 8A, 8B, 10A, and 10B, the punch PU has an inclined portion PU1 projecting toward the lower surface side of the stator blade 71 from the outer circumferential rim 73 a for forming the outer circumferential side support portion 76 of the stator blade 71. The punch also has an inclined portion PU2 projecting toward the lower surface side of the stator blade 71 from the inner circumferential rim 72 a for forming the inner circumferential side support portion 75 of the stator blade 71. The punch PU includes a punch main body portion PU3 having an inclined surface PU3 a projecting toward the front end side portion 77 from the bent portion 70R of the stationary blade portion main body 70H of the stator blade 71, the inclined surface being formed to be upgrade toward the outer circumferential rim 73 a from the inner circumferential rim 72 a. An abutting end PU3 b substantially parallel to the axial direction of the rotor shaft 5 is formed at a position of the punch main body portion PU3 corresponding to the front end side portion 77. The abutting end PU3 b is to separate the front end side portion 77 of the stator blade 71 from the stationary blade portion main body 70H.

As shown in FIGS. 9A, 9B, 10A, and 10B, the die DI has an inclined portion DI1 recessed toward the upper surface side of the stator blade 71 from the side of the outer circumferential rim 73 a for forming the outer circumferential side support portion 76 of the stator blade 71. The die also has an inclined portion DI2 recessed toward the upper surface side of the stator blade 71 from the side of the inner circumferential rim 72 a for forming the inner circumferential side support portion 75 of the stator blade 71. The die DI includes a die main body portion DI3 having an inclined surface DI3 a recessed toward the front end side portion 77 from the bent portion 70R of the stationary blade portion main body 70H of the stator blade 71, the inclined surface being formed to be downgrade toward the outer circumferential rim 73 a from the inner circumferential rim 72 a. An abutting end DI3 b substantially parallel to the axial direction of the rotor shaft 5 is formed at a position of the die main body portion DI3 corresponding to the front end side portion 77. The abutting end DI3 b is to separate the front end side portion 77 of the stator blade 71 from the stationary blade portion main body 70H.

The half-disc plate 70P is set on the die DI, the punch PU is pushed out in the arrow direction, and the drawing is performed to the half-disc plate 70P, so that the stator blade 71 is manufactured. In this drawing, a three-dimensional plastic flow is generated in the region 76 a of the diagonal lines of FIG. 7, so that the outer circumferential side support portion 76 is formed. By the plastic deformation of the region 76 a, the opening 82 is three-dimensionally deformed in the blade height direction from a flat shape, so that the opening portion 78 is formed. The stationary blade portion main body 70H stands up from the bent portion 70R (refer to FIG. 6) into an inclined shape in such a manner that the cut line 81 formed in the half-disc plate 70P becomes the front end side portion 77, so that the stator blade 71 is formed. A space between the front end side portion 77 of the standing stator blade 71 and the stationary blade portion main body 70H becomes the exhaust opening 79 (refer to FIG. 4). The opening portion 78 formed in an outer circumferential side part of the stator blade 71 is formed so as to be connected continuously to the exhaust opening 79.

According to the above embodiment described above, the following effects are obtained.

In the vacuum pump of the embodiment, the abutting ends FA1 and FB2 of the two divided stationary blade portions 70A, 70B are abutted with each other and the abutting ends FB1 and the FA2 are abutted with each other, so that the disc shape stationary blade portion 70 is formed. Each of the divided stationary blade portions 70A, 70B has the outer circumferential rim 73 a, the inner circumferential rim 72 a positioned in a front end on the inner circumferential side of the stationary blade portion 70, and the exhaust openings 79 and the stator blades 71 provided between the outer circumferential rim 73 a and the inner circumferential rim 72 a. The stator blades 71 are extended in a radial manner with predetermined width in the circumferential direction between the outer circumferential rim 73 a and the inner circumferential rim 72 a, and inclined at a predetermined blade angle with respect to the stationary blade portion main body 70H so as to form the plurality of exhaust openings 79. In the abutting ends FA1, FB2 (FB1, FA2) of the outer circumferential rims 73 a, 73 b where the plurality of divided stationary blade portions 70A, 70B is abutted with each other, in at least the one outer circumferential rim 73 a (73 b), the cutout K forming a gap from the other facing outer circumferential rim 73 b (73 a) is formed.

Therefore, even in a case where the circumferential length between the abutting ends FA1 and FA2 or FB1 and FB2 is formed to be longer than the designed size due to variation at the time of working, at the time of assembling the stationary blade portion 70, the ends of the outer circumferential rims 73 a of the divided stationary blade portions 70A and 70B can be suppressed from being overlapped with each other, or generation of warpage can be suppressed. In particular, the outer circumferential rims 73 a are nipped by the spacers. Thus, when the ends of the outer circumferential rims 73 a are overlapped with each other, positioning precision of the stationary blade portion 70 in the rotation shaft direction is deteriorated or the stationary blade portion 70 is not horizontally arranged but inclined. However, in the present embodiment, the ends of the outer circumferential rims 73 a are not overlapped with each other. Thus, the positioning precision of the stationary blade portion 70 can be improved, so that the stationary blade portion 70 can be horizontally arranged. This effect is a unique and remarkable effect which cannot be obtained from Japanese Unexamined Patent Application Publication No. 2006-77713 described above.

Each of the divided stationary blade portions 70A, 70B is manufactured from a flat plate into the same shape. An abutting end surface of the inner circumferential rim 72 a and an abutting end surface of the outer circumferential rim 73 a are formed as a first abutting surface in the one abutting end FA1 of the divided stationary blade portion 70A. An abutting end surface of the inner circumferential rim 72 a, an abutting end surface of the outer circumferential rim 73 a, and an abutting end surface of the edge member 70S forming the exhaust opening 79 are formed as a second abutting surface in the other abutting end FA2. The first abutting surface and the second abutting surface are abutted with each other so as to form the stationary blade portion 70. Therefore, the stationary blade portion 70 can be formed by combining two divided stationary blade portions of one type, so that cost can be suppressed.

Embodiment 2

FIG. 11 is an enlarged perspective view of Embodiment 2 in major parts of the stationary blade portion of the present invention.

In Embodiment 2, different points from Embodiment 1 are as follows.

(1) In each of the divided stationary blade portions 70A, 70B, an outer circumferential side support portion 76A for connecting the stator blade 71 and the outer circumferential rim 73 a or 73 b is formed over the entire length of the outer circumferential side end 71So of the stator blade 71 as well as the inner circumferential side support portion 75. That is, the opening portion 78 formed in Embodiment 1 for separating the front end side portion 77 from the outer circumferential side support portion 76 is not provided. (2) Bending portions 72 a 3, 72 b 3 bent at the substantially right angle from the abutting ends of the inner circumferential rims 72 a, 72 b are respectively provided in the inner circumferential rims 72 a, 72 b of the divided stationary blade portions 70A, 70B.

In a case where a blade height of the outer circumferential side support portion 76A is not really high, without providing the opening portion 78 for separating the front end side portion 77 of the stator blade 71 from the outer circumferential side support portion 76, no cracking is generated in the outer circumferential side support portion 76A. Therefore, by providing the outer circumferential side support portion 76A over the entire length of the outer circumferential side end 71So of the stator blade 71, rigidity can be further enhanced.

By respectively providing the bending portions 72 a 3, 72 b 3 bent at the substantially right angle from the inner circumferential rims 72 a, 72 b in the inner circumferential rims 72 a, 72 b of the divided stationary blade portions 70A, 70B, a task of abutting the bending portions 72 a 3 and the 72 b 3 with each other is easily performed. Therefore, a task of assembling the stationary blade portion 70 can be efficiently performed.

In Embodiment 2, the same operations and effects as Embodiment 1 can be obtained.

Other elements are the same as Embodiment 1, corresponding configurations are given the same reference signs, and description thereof will be omitted.

It should be noted that although the bending portions 72 a 3, 72 b 3 are respectively formed in the divided stationary blade portions 70A, 70B in the example, the bending portion 72 a 3 or 72 b 3 may be formed in only one of the divided stationary blade portions 70A, 70B.

In the structure of Embodiment 1, the bending portions 72 a 3, 72 b 3 may be provided in both the members of or one of the divided stationary blade portions 70A, 70B.

Embodiment 3

FIG. 12 is an enlarged perspective view of Embodiment 3 in the major parts of the stationary blade portion of the present invention.

In Embodiment 3, different points from Embodiment 1 are as follows.

(1) The divided stationary blade portions 70A, 70B include no outer circumferential side support portion for connecting the outer circumferential side end 71So of the stator blade 71 and the outer circumferential rim 73 a, and no inner circumferential side support portion for connecting the inner circumferential side end 71Si of the stator blade 71 and the inner circumferential rim 72 a. That is, the inner and outer circumferential side ends 71Si, 71So of the stator blade 71 are respectively separated from the inner and outer circumferential rims 72 a, 73 a or 72 b, 73 b over the entire length. (2) Only the one divided stationary blade portion 70B among the divided stationary blade portions 70A, 70B includes the bending portion 72 b 3 bent at the substantially right angle from the inner circumferential rim 72 b in the inner circumferential rim 72 b, and the other divided stationary blade portion 70A does not include a bending portion.

In a case where the blade height of the stator blade 71 from the stationary blade portion main body 70H is not really high, there is no need for providing the inner and outer circumferential side support portions 75, 76.

Thereby, a die can be inexpensive and production efficiency can be enhanced.

Even when the bending portion 72 b 3 is provided in only one of the divided stationary blade portions 70A, 70B, in comparison to a structure where no bending portion is formed, the task of abutting the end 72 a 1 and the bending portions 72 b 3 with each other is easily performed, and the task of assembling the stationary blade portion 70 can be efficiently performed.

Also in Embodiment 3, the same operations and effects as Embodiment 1 can be obtained.

Other elements are the same as Embodiment 1, corresponding configurations are given the same reference signs, and description thereof will be omitted.

It should be noted that in Embodiment 3, the inner and outer circumferential side support portions 75, 76 may be provided in one of inner and outer circumferential side parts of the divided stationary blade portions 70A, 70B, and no inner and outer circumferential side support portions 75, 76 may be provided in the other.

As described above, the stationary blade portions 70 are arranged in multiple stages in parallel to the axial direction of the rotor 4, and the blade height of the stator blade 71 is formed to be higher in the stationary blade portion 70 on the upper stage side than the stationary blade portion 70 on the lower stage side.

Therefore, the stationary blade portions 70 shown in Embodiments 1 to 3 may be differentiated in each stage. For example, the stationary blade portion 70 of Embodiment 1, the stationary blade portion 70 of Embodiment 2, and the stationary blade portion 70 of Embodiment 3 can be arranged in this order from the upper stage side toward the lower stage side. An uppermost stator blade 71 a may be the stationary blade portion 70 manufactured by mechanical working.

The cutouts K provided in the outer circumferential rims 73 a, 73 b in the above configuration are not necessarily provided in all the stages of the stationary blade portions 70 but may be provided in only at least one stage of the stationary blade portion 70.

In the example, the cutout K is provided in one side end of the outer circumferential rim 73 a or 73 b of each of the divided stationary blade portions 70A, 70B. However, the cutouts K may be provided in both side ends of the outer circumferential rim 73 a and 73 b.

The divided stationary blade portions 70A, 70B are not necessarily halved parts but may be not less than three divided parts.

In the example of the above embodiment, the compound type turbo-molecular pump including the blade exhaust portion and the threaded groove exhaust portion is shown as an example of a vacuum pump. However, the present invention can also be applied to a vacuum pump including only a blade exhaust portion.

In addition, the present invention can be applied with various modifications within a range of the gist of the invention. That is, as long as the present invention is a vacuum pump having an exhaust function portion in which stationary blade portions nipped by spacers are respectively arranged between rotating blade portions arranged in multiple stages, wherein in abutting ends of outer circumferential rims where a plurality of divided stationary blade portions is abutted with each other, in at least one of the outer circumferential rims, a cutout forming a gap from the other facing outer circumferential rim is formed, the invention is not limited to the embodiment and modified examples. 

What is claimed is:
 1. A vacuum pump having an exhaust function portion in which stationary blade portions nipped by spacers are respectively arranged between rotating blade portions arranged in multiple stages, wherein each of the stationary blade portions is formed by two or more divided stationary blade portions, each of the divided stationary blade portions has abutting ends in both circumferential ends, the stationary blade portion is formed by abutting the abutting ends of the divided stationary blade portions with each other, each of the divided stationary blade portions has an outer circumferential rim nipped by the spacers, an inner circumferential rim positioned in a front end on the inner circumferential side of the stationary blade portion, and a plurality of stator blades formed between the outer circumferential rim and the inner circumferential rim, and in abutting ends of the outer circumferential rims where the plurality of divided stationary blade portions is abutted with each other, at least one of the outer circumferential rims has a cutout forming a gap together with the other facing outer circumferential rim.
 2. The vacuum pump according to claim 1, wherein each of the divided stationary blade portions is manufactured from a flat plate into the same shape, an abutting end surface of the inner circumferential rim and an abutting end surface of the outer circumferential rim are formed as a first abutting surface in the one abutting end of the divided stationary blade portion, an end surface of the inner circumferential rim, an end surface of the outer circumferential rim, and an end surface of an edge member forming an opening portion are formed as a second abutting surface in the other abutting end, and the first abutting surface and the second abutting surface are abutted with each other so as to form the stationary blade portion.
 3. The vacuum pump according to claim 1, wherein the cutout is provided in the outer circumferential rim as a rectangular shape with a predetermined width in the circumferential direction and a predetermined length in a radial direction.
 4. The vacuum pump according to claim 1, wherein a bending portion bent from the inner circumferential rim is provided in at least one of end surfaces of the inner circumferential rims where the plurality of divided stationary blade portions is abutted with each other.
 5. The vacuum pump according to claim 1, wherein the gap is determined based on maximum tolerance α of circumferential length between both the abutting ends, and/or maximum tolerance β between an outer circumferential surface of the stationary blade portion assembled from the divided stationary blade portions and an inner circumferential surface of the spacer. 